Milling machine



Dec. 22, 1936. H ERNST Er AL `2,065,326 A MILLING MACHINE Filed sept.10, 1935 7 shetsfsheet 1 j Zia 7 I /zz I /7 la WH T5517. HECHEHATTORNEY.

Dec. 22, 1936. H. ERNST Er AL 2,065,326

MILLING MACHINE Filed sept. 1o, 1935 7 sheets-sheet 2A INVENTOR. #ausERNST Me/0 5. MnKTE/.L om WHLTEK 17. Fine/15H ATTORNEY.

Dec. 22, 1936. H, ERNST ET AL 2,065,326

MILLING MACHINE Filed Sept. l0, 1935 7 Sheets-Sheet hm ww wl Nw m V|l!|.i. m u www i Dec. 22, l936 H. ERNST Er Al. 2,065,326

MILLING MACHINE Filed sept. 1o, 1935 7 sheets-sheet 4 y I uq l .T 4/m/Ys Efe/V57 Za Me 21o E .MARTEL/ om BY wenn? J. Hee-Hm www L ATTORNEY.

Dec. 22, 1936. H. ERNST ET A1. 2,065,326

MILLING MACHINE Filed sept. 1o, 1955 7 sneetssheet 5 ma OE KTuH NNN mwm@ I w?? 65 N3 N w m m a. \m5MB I www ,i mm Q 4 Y N B NNN ,WW/@3mmATTORNEY.

Dec. 22, 1936. H. ERNST ET AL 2,065,326

MILLING MACHINE Filed Sept. 10, 1935 7 SheetS-Sheet 6 S Nw I Dec. 22,1936. H. ERNST ET Al. 2,065,326

MILLING MACHINE Filed Sept. 10, 1935 'T Sheets-Sheet 7 l\ "'5 N Q N N wH H N H M, w sa w 7 F j@ f2 E N 7 y H Q. @l a Z @1 o N e s l n 1*INVENTOR.

HHNsE/ensr BY Maz/o E. MnkTELLom WHL TERE. ARCHE/ www ATTORNEY.

Patented vDec. 22, 1936 MILLING MAC Hans Ernst, Mario E. Martellotti,and Walter D.

Arcliea, Cincinnati, Dhio, assignors to The Cincinnati Milling MachineCo., Cincinnati, Uhio, a corporation of Ohio Application September 10,1935, Serial No. 39,950 13 Claims. (Cl. Sil-21.5)

This invention relates to milling machines Figure 11 is a sectional viewthro-ugh the rate and more particularly to an improved transvalve.mission and control mechanism therefor. Figure 12 is a view showing theoperating con- One of the objects of this invention is to pronections tothe stop valve and the pilot valve. vide an hydraulically operatedmilling machine Figure 13 is a detailed section on the line 5 which willperform climb cutting operations in l3-l3 of Figure 12. a more eiicientand practical manner than here- Figure 14 is a diagrammatic view of thehytofore. draulic control circuit.

Another object of this invention is to provide Figure 15 is a sectionthrough the pilot valve an hydraulic control mechanism of the servoasviewed on the line lli-I5 of Figure 12.

type in which the servo-valve may be remotely Figure 16 is a rolled-outview of the pilot valve located with respect to the moving part,Whereplunger. bythe entire hydraulic control mechanism may Figure 17 isa modied form of connection be built as a unit for insertion in themachine. between the table and servo-valve.

A further object of this invention is to provide Figure 18 is a detailsection on the line IIB-i8 15 a milling machine with a servo-controlmechyof Figure 17. anism while retaining the other desirable fea- Amachine embodying the principles of this tures of automatic rate anddirection control, invention is illustrated in Figure 1 and comprisesselective automatic stop, and variable feed rate a bed I0 upon which isformed a guideway for zu selection. receiving a horizontally movablework table Il. Other objects and advantages of the present This table isadapted for moving a work piece invention should be readily apparent byreferin a direction transversely to the axis of the ence to thefollowing specification, considered in cutter spindle l2 upon which acutter I3 is conjunction with the accompanying drawings supported forrotation. forming a part thereof and it is to be under- 'I'his cutterspindle is journaled in a carrier stood that any modifications may bemade in it which is vertically adjustable on guideways the exactstructural details there shown and del5 through suitable conventionalmechanism scribed, within the scope of the appended claims, formed onthe column portion i6. This makes without departing from or exceedingthe spirit it possible for the cutter to be adjusted relaof theinvention.

Referring to the drawings in which like referof cut. A transmissionmechanism not shown ence numerals indicate like or similar parts: may beprovided for rotating the cutter spindle Figure 1 is a front elevationof a machine tool in either direction and this mechanism may beembodying the principles of this invention. the same as that shown inco-pending United Figure 2 is a section through the hydraulic Statesapplication, Serial Number 220,721, led 3'5 control unit as viewed onthe line 2 2 of Fig- September l5, 1927, and therefore, further defab'ure l. scription thereof is not believed to be necessary. Figure 3 is asection on the line 3 3 of Fig- In milling machine practice there aretwo ure 2. recognized ways in which a cutting operation 40 Figure 4 is asection on the line 4 4 of Figmay be performed and these aredierentiated ure 3 showing part of the mechanism for actuby thedirection in which the cutter rotates as ating the servo-valve. respectsa common feeding direction of the Figure 5 is an elevational View asviewed on table. In other words, the cutter may be rothe line 5 5 ofFigure 4 showing the operating tated counterclockwise, as viewed inFigure 1,

connections to the servo-valve. and the table moved to the left, inwhich case 45 Figure 6 is a detail section on the line 6 6 it will beapparent that each cutter tooth exerts of Figure 4. a force in adirection opposed to the direction Figure l7 is a detailed section onthe line I l of movement of the table, or in other words, the of Figure4. cutter opposes the force that feeds the table.

Figure 8 is a detail section through one of On the other hand, thecutter may be rotated 50 the relief valves. in a clockwise directionwith the table still be- Figure 9 is a detail view of the feed ratethroting moved toward the left, which results in the tle and operatingconnections therefor. cutter tooth tending to advance the table in theFigure. 10 is a detail section on the line I0 Ill same direction inwhich it is feeding. 5 of Figure 3 showing the brake mechanism. In thelatter case, the feeding mechanism has 55 tive to the work table il todetermine the depth su to exert a force in such a direction and ofsufficient amount to overcome any tendency for the cutter to usurp thefunction of the feeding mechanism and yet maintain a uniform feed rateif the work is to be properly nished. Although hook-in cuts, as thelatter are known in the art, have been accomplished in the past, theresults have not been very satisfactory. This invention deals with amechanism which makes it possible to take the hook-in cut in a verysteady manner and with no perceptible difference in results than if thecut were taken in another manner.

The transmission and control mechanism forming the basis of thisinvention is hydraulic in nature but differs from known hydrauliccircuits for this purpose in that a servo-motor mechanism is utilizedand even this mechanism is so contrived that the servo-valve may beremotely located with respect to the` moving part. This is accomplishedby using a servo-valve of therepositioning type as distinguished fromthe follow-up type whereby the servo-valve housing and its plungerremain in substantially a xed position at all times.

The entire hydraulic mechanism is mounted in a single bracket which maybe removed and inserted as a unit in the bed of the machine andconstitutes in a sense a centralized power unit.

The table is actually moved by a piston I1 contained in a cylinder I8and connected by a piston rod I9 to one end of the table. The cylindermay be mounted on the top of the bed, as shown in Figures 1 and 3, andintermediate the table guideways formed thereon while the servovalveindicated as a unit by the reference numeral 20 may be located in abracket 2| which is detachably mounted on one end of the bed whereby theservo-valve is remotely located with respect to the table |I andcylinder I8. The connections to this valve from the cylinder are shownin Figure 14, and comprise a channel 22 which extends from port 23 ofthe servo-valve to the right hand end of the table cylinder and achannel 24 which extends from port 25 to the left hand end of the tablecylinder. This valve has a pressure port 26 which is connected bychannel 21 to the output 28 of a constant pressure variable deliverypump 2S, which is commercially known as an accumulator pump.

The servo-valve also has ports `3|) and 3| which are connected by acommon return line 32 to the intake side 33 of the accumulator pump. Theoutput 28 of the pump is connected by channel 34 to a cylinder 35 inwhich is contained a piston connected to pump pendulum, a spring beingutilized to exert an opposing force to the hydraulic pressure wherebywhen the `pressure rises too high the pendulum will be moved in adirection to reduce the volumetric flow from the pump, and when thepressure drops the pendulum will be moved in a direction to increase theilow.

The servo-valve has a central spool 36, which is slightly narrower thanthe width of the port 25, to allow a continuous iiow from the pressureport past both sides of the spool when the same is in a centralposition, or the spoolmay be slightly greater in width than the width ofthe annular groove but with the corners beveled a suflicient amount tostill permit a continuous iiow from the annular groove 26 when the spool36 is central with respect to the port. The space allowed for the flow,however, is very small and constitutes, in eiect, a pair of hydraulicresistances connected in parallel to the port 26 whereby a pressure dropwill occur between this port and the spaces formed around the Valveplunger 31 by the cannelures 38 and 39. In addition, these canneluresare of sufficient axial length that there is some flow from eachcannelure through each port 30 and 3| when the spool 36 is centrallylocated with respect to the pressure port. The result of this is thatthere is formed an hydraulic resistance to the flow of duid from thecannelures to the channel 32, causing another drop in pressure, wherebythe pressure in channel 32 is lower than the pressure in eithercannelure and the pressure in either cannelure is lower than thepressure in the supply channel 21. Since the ports 23 and 25 are incontinuous connection with these cannelures, the pressures existingtherein will be communicated to opposite ends of the cylinder whereby asubstantial holding pressure exists therein at all times, regardless ofwhether the table is stationary or moving. This distinguishes from otherservo-valve mechanisms in which the spool 36 is of equal width withrespect to the pressure port so that when the servo-valve is in acentral position no flow occurs to the cylinders; and also in the fa'ctthat even when the valve is moved from its central position there isstill some division of flow whereby the pressure in either end of thecylinder never drops to atmospheric pressure.

In order to cause movement of the table it is necessary to move theservo-valve piston from its central position.

One form of servo-valve operating mechanism is shown in Figures 3, 4 and5. In Figure 5 it will be noted that the servo-valve plunger 31 isconnected to a rod 40 having a head 4| on the end thereof and a spring42 is interposed between this head and a bracket 43 fixed to the valvehousing whereby the spring tends to cause movement of the plunger 31toward the right. The rod 4D, however, abuts the end of a slidable rod44 which, in turn, is interposed between the end of the head 4| and alever arm 45. The opposite side of the lever 45 is engaged by a button46 carried by the lever arm 41, this lever arm being bolted to a disc 48xed with a shaft 49, as more particularly shown in Figure 4.

The shaft 49, as shown in Figure 6, has a pinion 50 secured theretowhich intermeshes with a pinion 5|, which, in turn, engages an internalgear 52. As shown in Figure 4, this internal gear is integral with aworm gear 53 meshing with a worm 54.

Referring to Figure 3, the worm 54 is journaled at opposite ends inanti-friction bearings 55 and 56 and at one end has an operativeconnection to an hydraulic motor 51 and at the other end a selectiveclutch connection to a hand wheel 58. This connection comprises a clutchmember 59 which is fixed with the shaft 60 which supports the worm 54,and a shiftable clutch member 6| which is slidably mounted on the end ofa rotatable shaft 62. A spring 63 is mounted interiorly of the shaft 62and engages a cross pin 64 xed with the member 6| by which the same isconnected for rotation with the shaft 62 and acts in a direction tomaintain engagement of the clutch whereby the hand wheel 58 is normallyconnected to the shaft 60. The shaft 62, however, has a shoulder 65formed thereon which is mounted in a cylinder 66 whereby when fluidpressure is admitted to this cylinder, the shaft 62 will be moved in adirec- Cil tion to disengage the clutch teeth. The hydraulic connectionsare such that pressure will be admitted to this cylinder at all timeswhen the machine is being power operated. Y

If it is assumed that the member 6| is in engagement with the member 59the hand wheel 58 may be rotated, thereby causing rotation of the wormwheel 53, and through the internal gear 52 and pinion 5|, will causerotation of the pinion 50 and thereby movement of the arm 41 shown inFigure 5 in a clockwise direction, which will shift the servo-valveplunger v31 to the left and cause admission of fluid through one of thechannels 22, 24 to the cylinder i8, and thereby movement of the table.

Movement of the table is transmitted to the servo-valve to repositionthe same by means of a steel tape 61 which is connected at one end tothe table by means of bolts 68, and at the other end to a reel B9. Thetape passes over the roller 18 located on top of the bracket 2|. Thereel 89 has a removable section 1| by which the same may be securelyanchored to the reel. The reel 89 is secured by a set screw 12 to shaft13, Figure 4, this shaft having a spur gear 14 xed therewith andintermeshing with gear 15. The gear 15 is supported for free rotationabout the sleeve 1B in which the shaft 49 is journaled. The gear 15 hasthe pinion 5| secured thereto whereby upon rotation, of the reel, theplanetary gear 5| will be moved, and since the internal gear 52 is heldstationary by the intermeshing worm and worm gear 53, 54 the pinion 59will be rotated in a direction to cause movement of the arm 41 in anopposite direction to that in which it was moved by the hand wheel 58whereby the servo- Valve will be returned to a. central position andmovement of the table will be stopped.

Although it would seem from the foregoing description that there isconsiderable time -elapse between rotation of the hand wheel 58 and thereturn movement from the table, there is actually no perceptible timelapse, the repositioning movement occurring to all intents and purposesalmost simultaneously with the initiating movement.

The mechanism for causing power feeding movement of the table at auniform rate consists ofthe hydraulic motor 51 which may be rotated atvariable feed rates or at a fast or quick traverse rate and since theenergy required to rotate the worm and worm wheel and move theservo-valve is very small, this motor may of course be of a very lighttype.

As shown in Figure 14, of the drawings this motor 51 has a pair of ports11.and 18 which are connected by channels 19 and 80 to ports 8| and 82of a stop valve 83 having a plunger 84. This valve plunger has acannelure and a second cannelure 86 which, when the plunger is in arunning position, connects ports 8| and 82 to ports 81 and 88respectively. The port 81 is connected by channel 89 to ports 90 and 9|of a direction control valve 92 having a reciprocable plunger 93. Theport 88 is connected by channel 94 to port 95 of the direction orreversing valve 92. When the plunger 93 is in one position, a cannelure96 therein connects port 95 to the exhaust port 91, and a cannelure98-connects port 9| with a pressure supply port 99. If the plunger isshifted toward the right to its other extreme position, the pressureport 99 is connected to port -and port 90 is connected by cannelure |00to port 91 which will thereby cause rotation of the motor 51 in anopposite direction.

withdrawn from a reservoir |03, delivers fluid- Yinto a channel, |04which has a connection to port |05 of the rate control valve |96 .inwhich is reciprocably mounted a plunger |81. When this plunger is in theposition shown, a cannelure |08 therein connects port |95 to port |99,and thereby, through channel H9, to port of the servo-control valve. Theservo-valve has an annular groove ||2 formed therein which is adapted toconnect port with port H3 at all times during normal movement of thevalve. The port ||3 is connected by channel H4 to the pressure port 99.The object of providing the connection through the servo-valve is merelyfor safety reasons so that in case the servo-valve gets too far ahead ofthe movement of thetable the supply to the motor 51 will beautomatically reduced.

'I'he exhaust port 91 of reversing valve 92 is connected by channel H4to port H5 of the rate valve, and thereby through cannelure |56, whenthe valve is in the position shown, to port ill and thereby, throughchannel H8, to port ||9 of the throttle valve I 20. This throttle valvehas a plunger |2|, which may be variably set by rotation of theconflgurated cam |22 to various positions to control the rate ofrotation of the hydraulic motor 51 and thereby the feed rate imparted tothe table. A spring |23 maintains the plunger in engagement with theperiphery of the cam |22. This valve has an exhaust port |24 which isconnected by channel |25 to the reservoir |93.

To insure that the line H9 is properly supplied with fluid, a checkvalve |26 is interposed for connecting the return channel 32 of pump 29to channel ||3 and the check valve is set to insure additional :dow intothe channel when the pressure therein drops below a predeterminedminimum. The channel H9 also has a connection at |21 to port |28 of arelief valve |29.

'Ihe specic construction of this relief valve is shown in Figure 8 andcomprises a plunger |30 which is acted upon at one end by a spring |3|which may be set to yield desirable pressures by adjustment of thesleeve |32 in which the spring is contained. 'Ihis plunger has acannelure |33 by which port |28 may be interconnected to an exhaust port|34. The plunger also has a diametrical bore |35 which communicates withan axial bore |36 in which is mounted a spring pressed ball |31 whichnormally acts to close the axial bore and prevent discharge of fluidthrough port |29. The spring |38 which acts on the ball |31 is a hightension spring and the spring |3| normally acts to position the plunger|30 so that the port |28 is entirely closed. Should a high pressureresult at port |28 it will act to open the relief valve ball |31 andcause a flow to the chamber |39-which will act, in turn, on the end ofthe plunger and shift the same against the resistance of spring |3|suiiicient to cause the cannelure |33 to interconnect port |29 with port|34. The chamber |39 may be connected by a channel |49 to channel H8. Itwill be remembered that the channel H8 is the return channel from themotor 51 and that the pressure existing therein will bev com municatedto the right hand end of valve |29 normally urging the same to an openposition. The spring |3| will be so set, however, that this will notoccur unless an excessive high pressure occurs in channel due toresistance of the motor, at which time the additional fluid escapingpast the high pressure relief ball |31 will cause the pressure inchamber |39 to rise sufliciently to overcome the resistance of spring|3I.

A second relief valve |4I, which is exactly of the same construction asthe relief valve |29, has its port |42 connected to a branch line |43 ofchannel |04. The chamber |39 of this valve is connected by a channel |44to reservoir, but this channel has a choke coil |45 arranged therein,which in eiect is an hydraulic resistance which will maintain a smallpredetermined pressure in chamber |39. The channel |44 has a branch |46which is connected to port |41 of the stop valve 83. The function ofthis connection is that when the stop valve is shifted to the left fromthe position shown in Figure 14 to a stop position to interconnect ports81 and 88, a considerable rise in pressure occurs, due to the suddenstoppage of flow and this rise in pressure is immediately communicatedthrough the connections described to chamber |39 of the relief valve |4|Should this pressure rise beyond a predetermined amount determined bythe setting of the valve |4| the plunger |48 of the valve will shift tointerconnect port |42 to port |49, and thereby relieve the pressure inchannel |04. The discharge from port |49 is delivered into channel ||0which is the motor supply line.

The pump |0| is connected to a check Valve |50 to the supply line 21 ofthe Servo-valve. During feed movements of the table the pressure in line21 is considerably higher than the pressure in line |04 and the checkvalve |50 will normally remain closed. During quick idling movements ofthe table at rapid rates, the pressure in line 21 will naturally drop,and the pump |0| is then enabled to augment the delivery of pump 29 andinsure a plentiful supply of fluid to maintatin the rapid movement.

Since the pump 29 s connected in substantially a closed circuit with thecylinder I8, a bypass valve has been provided whereby the pump |0| maybe enabled to fill this closed circuit with fluid from the reservoir |03when the machine is first started. The valve is utilized for thispurpose, and has port |52 connected by branch |53 to the delivery ofpump |0|, and a second port |54, which is adapted to be connected toport |52 by the cannelure |55, formed in the valve plunger |56. When nopressure exists in the lower end of the valve the spring |51 moves theplunger so that the ports are interconnected and fluid will flow throughchannel |58 to the intake port of pump 29. When the pressure in thereturn line of pump 29 rises to a predetermined maximum the uid leakingthrough the hydraulic resistance |59 to the lower end of plunger |56will cause the same to move against the resistance of spring |51 andclose port |54. This valve thus acts to automatically supercharge thereturn line of pump 29 when the machine is first started or at any timethat the fluid supply in the circuit falls below a predeterminedminimum.

The mechanism for operating the stop valve is more particularly shown inFigure 12 and from that gure it will be noted that a spring |60 isinterposed between an abutment I6I, and a flange |62 formed on theplunger 84 normally acts in a direction to shift the valve to the left,or in other words, to a stop position. The plunger 84, however, has alost motion connection at |63 with a crank arm |64, which has a manualcontrol lever |65 integral therewith. A second crank arm |66, integralwith lever |65, has a ball-shaped end |61 interfitting in a slot |68formed in the end of rod |69. This rod is connected through the bellcrank to the latch pawl |1I. This pawl interts in a slot |12 formed inthe member 84 to hold the same in the position shown against thecompression of spring |60. The bell crank |10 also has a connection at|13 with a stop trip plunger |14. This plunger is surrounded by a springwhich is interposed between an abutment |16 and ange |11 formed on theplunger, which normally acts in a direction to move the plungervertically upward. This movement is limited, however, by the pawl |1|bearing on the rod 84. This insures that the pawl |1| will drop into theslot |12 at any time that the plunger 84 is moved to a position topermit this. The manual or control lever |65, when rotated in aclockwise direction, as viewed in Figure 12, will rst move the rod |69to the left, causing withdrawal of the pawl |1| and the lost motion inconnection |63 will permit this to be done. When the pawl |1| has beenremoved from the slot, the spring |60 will come into action to shift thestop valve to its stop position.

This may also be accomplished automatically by means of a stop dog |18which may be secured in a T slot |19 formed in the edge of the table II.

It will be recalled that earlier in the specification reference was madeto the fact that the cylinder 66 associated with the clutch 6| thatdetermines the coupling of the hand wheel 58 with the worm 54 wassupplied with pressure when the machine was being power operated, andthis supply of pressure comes from the high pressure channel 21 throughan hydraulic resistance |80. This resistance may be in the form of achoke coil which will cause a considerable drop in pressure to channel|8| which leads to this cylinder. This channel, however, has a branch|82 which is connected to port |63 of stop valve 63. When the stop valveplunger is shifted to the left to a stop position, the port |83 isconnected to reservoir through the end of the valve housing due to thefact that the spool |84 has moved a sufficient distance to accomplishthis result. From this it will be seen that even though there will be acontinuous leakage through the choke coil |80 there will not besufficient to build up pressure in cylinder 6| due to the openconnection at port |83, whereby the operator is enabled to move the rod65 longitudinally to effect engagement of the clutch. This acts as aninterlock and insures that the operator can only utilize the manualcontrol lever 58 when the hydraulic motor 51 is rendered inoperative bythe stop valve. Channel |8| also has a branch connection to a brake |8Iwhereby the brake is held in a released position against resistance of aspring as shown in Figure 10. This brake insures prompt stopping of worm54.

Since the stop valve merely closes ports 8| and 82, fluid will stillremain in channels 19 and 80 and in order to facilitate manual rotation,since the motor 51 is at all times connected to the worm 54, a by-passvalve has been formed in the shaft 62 and consists of a cannelure |85adapted to interconnect ports |86 and |81 which are connectedrespectively by channels |88 and |89 to the motor ports 11 and 18whereby when the motor is rotated due to rotation of the shaft 60 theuid will freely flow from one side of the motor to the other.

The rate and direction valve plungers are power shifted under thedirection of a pilot valve |90, which has a plunger |91 in which isformed three cannelures 92, |93 and 94. This valve has a port |95 whichis connected by channel 96 to a high pressure channel 21. This valvealso has a pair of ports |91 and |98 which are connected by channels |99and 200 to opposite ends respectively of the direction determining orreversing valve 92. When the valve plunger |91 is in the position shown,the port |98 is connected to the pressure port I 95 and fluid'isdelivered through channel 200 to the right hand end of the directionvalve which shifts the same' to the position shown and the other end ofthe direction valve is connected through channel |99 and port 91 toannular groove |92. 'Ihis groove has a radial hole 29| which intersectsan axial .bore 202 which extends the full length of the valve plunger,and is at all times connected with reservoir through a secondl axialhole 203 which communicates with the annular groove |94. This groove, atall times, communicates with port 204 which is connected by channel 205to the return line 25. When the valve is shifted to the'left thepressure port |95 is connected to port |91 which causes shifting of thevalve plunger 93 to the right and channel 200 is connected through port|98 to the exhaust annular groove |94.

Thus, by merely shifting the pilot valve axially the direction ofmovement of the table may be reversed.

The pump 51 is rotated at a fast or quick traverse rate when the ratecontrol valve plunger |01 is shifted tothe right from the position shownin Figure 14. At this time, the pressure port from pump |01 isdisconnected; the port |09 isolated; and the port |15 interconnected tothe return line |25.

Fluid is now suppliedto motor 51 from pump |01 through port |42 of valve|41, the plunger of vwhich opens sufliciently to permit iiow throughport |49 to channel |10. The flow in this channel is augme ted throughthe check valve 126. The retur ow from the motor passes through channel|14 to the return line |25. Thus, during rapid traverse movement of thetable the throttle valve does not function but whatever pressure existsat port |11 is communicated to the right hand end of valve 129 to causeopening of port |29 to reservoir, should there be an excess of fluid inchannel 1 10.

The feed-rapid traverse or rate selector valve 196has channels 206 and201 leading from opposite ends thereof to ports 298 and 209 of the pilotvalve. This valve also has a pressure port 211) which is connected bychannel 211 to ports 212 and 213 of the reversing valve 92. The objectof this is that when both the direction and rate valve have to beshifted atthe same time that the direction valve will be shifted first,thereby cutting off the supply to port 210 until the direction valve hascompleted its movement.

The pilot valve has two longitudinal slots 212 and 215 formed therein,and another pair similarly located but in 180 phase relation thereto.The plunger also has a second pair of slots 219 and 211 formed in 180phase relation with one another, but in 90 phase relation with respectto grooves 2111 and 215 and also in overlapping relation thereto Theplunger also has four exhaust grooves 218, 2|9, 220 and 221. When theplunger is in the position shown, the port 210 is connected by groove211 to port 209 and pressure is delivered to the right hand end of therate valve and the left end is connected, through channel 296, port 208and exhaust groove 2|9, to reservoir. This valve is rotatable through221/2 from the position to change the rate without changing thedirection, from which it Will be seen that a 221/2" rotation of plunger9| will position groove 2111 opposite holes 208 and 210' formed in portgrooves 208 and 210, thereby connecting pressure to the left end of therate valve |06 and thereby shifting the same to the right and connectingchannel 201 through port 209 to longitudnal groove 215. This groove isat this time in communication with a hole 222 in the bushing which, asshown in Figure 15, communicates with an annular groove 223, this groovebeing connected at this time by a second hole 224 in the bushing to theexhaust bore 202.

If the plunger 19| is shifted to the left from this position the groove215 will now interconnect the pressure port 210 to port 209 and groove211 will interconnect port 208 to exhaust in a manner similar to thatshown in Figure 15. In other words, each time the valve plunger 19| isshifted longitudinally from one position to the other or rotated whilein either one of these extreme positions, the rate of movement of thetable is changed. All of these various connections are shown in theexpanded View of the pilot valve shown in Figure 16 of the drawings.

The valve plunger 19| is connected through a universal joint 225, asshown in Figure 13, to the trip plunger 226 which has a wing 221 on oneside thereof `adapted to be engaged by dogs 228 and 229 to rotate thesame to shift the plunger |91 longitudinally. The plunger 226 is alsosupported for vertical movement and has a pair of lugs 230 and 23|adapted to be engaged` by dogs 232 and 233 for shifting the samevertically and thereby rotating the valve. In other Words, the rate maybe changed during continuous movement in either direction withoutchanging the direction. But when the plunger 226 is rotated to changethe direction it also changes the rate. This makes it possible to changefrom feed in one direction to a quick traverse movement in the otherdirection by a single movement of the valve. The plunger |91 may beprovided with a manually operable handle 2311 whereby the position ofAthe valve may be determined by the operator. h

In Figure 17 of the drawings is shown a modifled form of connectionbetween the table 1 and the servo-control valve and comprises a rack 235which is attached to the table and operatively engages a spur gear 236mounted on shaft 231 which has integral therewith a bevel gear 238. Thisbevel gear intermeshes with a bevel gear 239 secured to the upper end ofa shaft 210 which extends in an` angular relation to the servo-valvehousing. The lower end of this shaft has a beveled gear 2111intermeshing with a bevel gear 212 which is integral with the worm 2112which intermeshes with the Worm 51 which is the same as the worm shownin Figure 3. In this construction the shaft which supports the wormwheel has a shoulder 2111- against which bears a bronze ring 2115 havinga slot 226 formed therein. A nger 211 interts in this slot and is partof a lever 298 whichd is pivoted at 2119. The end of the lever 212 abutsthe servo-valve plunger 20. The bronze bushing 246 serves to CII reduceline contact and wear 0n the end of the finger 241. With the exceptionof the change in the mechanical construction of this return connectionto the servo-valve the operation is exactly the same.

There has thus been provided an improved machine for the purposesdisclosed which is simple to construct and operate.

What is claimed is:

l. Means for eecting relative feeding of the table and cutter of amachine tool including a piston and cylinder, one of which is connectedto the table and the other xed, a servo-valve having a plunger in whichis formed chambers which are connected to opposite ends of the cylinder,a source of pressure, uid resistances for connecting said source ofpressure to said chambers, additional fluid resistances connecting saidchambers to exhaust whereby a predetermined pressure exists in saidchambers and thereby in opposite ends of the cylinder, means toinversely vary the resistances between said pressure port and saidchambers to cause a pressure differential in said cylinder and resultantmovement of the table to cause the same to move at a predetermined rateunaffected by said cutter, and connections from said table and effectiveupon said resistances to reversely change the values thereof if the rateof movement uctuates due to action of the cutter.

2. A feed control mechanism for a milling machine or the like having abed, a table reciprocably mounted upon the bed and a cutter supported bythe bed for rotation in a direction whereby the teeth will move in thesame direction as the work during contact therewith, including acylinder supported by the bed and a contained piston operativelyconnected to the table, a source of pressure, a pair of variablehydraulic resistances connected to said source of pressure, saidresistances terminating in chambers at opposite ends of the cylinder, asecond pair of variable hydraulic resistances connecting said chambersto reservoir whereby pressures will be created in said chamberintermediate the supply pressure and atmospheric pressure, means toinversely vary the rst pair of resistances to cause a pressurediierential in opposite ends of the cylinder to cause movement of thetable at a predetermined rate, and means responsive to abnormal movementof the table created by the cutter to readjust said resistance andcorrect for the action of the cutter.

3. Power operable means for effecting relative movement betwei the tooland work supports of a milling machine or the like including anhydraulic motor, a source of pressure, a centralized control unitremotely located with respect to said motor, a servo-valve mounted insaid unit, means for shifting said valve to cause a ow to said cylinderand thereby operation of one of said supports, and a remote connectionfrom said support to said valve including a steel tape operativelyconnected to the support, a reel to which the other end of said tape isconnected, said reel being located in the unit, and a differentialmechanism responsive to movement of the reel for repositioning saidservo-valve and reduce the actuating flow to said cylinder.

4. Power operable means for effecting relative movement between the workand tool supports of a machine tool comprising a servomotor mechanismincluding a servo-valve, an hydraulic motor for actuating said valve inone direction, means operatively connecting the valve to one of saidsupports to cause repositioning of the valve, a control circuit for saidmotor including a. source of pressure, a direction determining valve, apilot valve for controlling power shifting of the direction valve, and atrip controlled plunger for actuating said pilot valve.

5. The combination with a servo-motor mechanism for actuating a machinetool support, of an hydraulic motor for power operating the servovaive,a source of fluid pressure, a reversing valve and a stop valve seriallyconnected between said source of pressure and said servovalve, a pair ofchannels extending from the stop valve to the motor, said stop valvealso having a pressure intake port and a return port connected to saidreversing valve, a relief valve in the pressure line, means in the stopvalve to interconnect said pair of ports to disconnect flow from themotor, and means connecting the stop valve to said relief valve wherebysudden high pressures created at the intake port of said stop valve uponmovement to a1 stop position will open said relief valve to lower theincoming pressure.

6. Means for actuating a movable support including a piston andcylinder, one of which is connected to the movable support, aservo-valve, a high pressure pump connected in closed circuit to saidservo-valve, an hydraulic motor for actuating said servo-valve, a returnconnection from the movable support for repositioning said servo-valve,a separate source of pressure for actuating said motor including a ratevalve, a direction determining valve, and a stop valve in theordernamed, means to position said rate Valve to connect said additionalsource of pressure to said motor for quick traverse operation thereof, athrottle valve, and means in said rate valve upon movement to a secondposition to connect the return line from said motor to saidthrottlevalve to cause operation of said motor at a variable feed rate.

'7. An hydraulic control system for a milling machine or the like havinga work support, and a tool support, including means for eiectingrelative movement between the supports including a piston and cylinder,each connected to one of the supports, a high pressure accumulator pump,valve means for connecting opposite ends of said pump to opposite endsof the cylinder, said valve means including a rst pair of hydraulicresistances connected in parallel to the output of said pump, a secondpair of hydraulic resistances connected in parallel to the input of saidpump, power operable means for simultaneously increasing one of saidfirst pair of resistances and decreasing the value of the other toincrease the pressure in one end of the cylinder and decrease thepressure in the other end, said power operable means also beingeffective to inversely vary the second pair of resistances to maintainsaid pressure differential during relative movement of the supports, andmeans operable by said movement tending to equalize the total pressuresin opposite ends of the piston to thereby stop the relative movementbetween the supports.

8. A transmission for a milling machine having a bed, a cutter spindlerotatably supported by the bed, and a work table mounted on the bed forrelative movement transversely to the axis of said spindle, saidtransmission means including a iirst hydraulic motor having a pistonconnected to the table, a servo-valve located in the bed for controllingactuation4 of said 75 motor, a second hydraulic motor for actuating saidservo-valve, an extensible connection from the table for repositioningsaid valve, and means to supply uid pressure to each of said motors.

9. 'Transmission means for effecting relative movement between thespindle and table of a milling machine or the like in a directiontransversely to theaxis of said spindle including a cylinder having apiston operatively connected for effecting said relative movement, meansto control actuation of lsaid piston including a first pair of seriallyarranged hydraulic resistances, and a connection between saidresistances to one end of the cylinder, a second pair of variablehydraulic resistances, and an-intermcdiate connection to the other endof said cylinder, means to pump fluid through said resistances wherebythe pressure in opposite ends; of said cylinder will depend upon theratio of the resistances of one -pair to the ratio of the resistances ofthe other pair, power operable means for continuously changing saidratios in a manner to create a pressure diierential on said piston, andmeans responsive to movement of the table to change said resistances inan opposite manner to reduce the pressure differential on said piston.

10. Means for effectingrelative movement or machine tool parts such as asupport and table including a piston' and cylinder, one of which isconnected to the table, a servo-valve for controlling operation of saidmotor, a second hydraulic motor for actuating said ,servo-valve, meansto supply uid pressure to each of said motors, a feed back connectionfrom the table to said servo-valve, means to predetermine the rate ofoperation of said second hydraulic motor and thereby predetermine thefeed rate of said table, and means responsive to undesirable changes inthe feed rate effected by said cutter to readjust said servo-valve.

11. Transmission means for control of the table of a milling machinehaving a tool spindle and a toothed cutter supported for rotationthereby and a Work table actuable in a direction parallel to thedirection of movement of the'teeth of said cutter while cutting, saidtransmission means including a piston and cylinder, one of which isoperatively connected to the table, a constant high pressure lpump fordelivering fluid to said' cylinder, a servo-valve for connecting saidpump in a manner to create equal resultant pressures in opposite ends ofsaid cylinder to hold the table against movement, a second hydraulicmotor for adjusting said servo-valve to create a suflicient pressuredifferential to cause feeding movement of the table at a predeterminedrate, and means responsive to abnormal changes effected in said rate bythe action of said cutting teeth during cutting to change said pressuredifferential ina manner to re-establish said predetermined rate.

12. Transmission means for control of thel table of a milling machinehaving a tool spindle and a toothed cutter supported for rotationthereby and a work table actuable in a direction parallel to thedirection of movement of the teeth of said cutter while cutting, saidtransmission means including a piston and cylinder, one of which isoperatively connected to the table, a constant high pressure pump fordelivering uid to said cylinder, a servo-valve for connecting said pumpin a manner to create equal resultant pressures in opposite ends of saidcylinder to hold the table against movement, a

second hydraulic motor for adjusting said servovalve to create a sucientpressure differential to cause feeding movement of the table at apredetermined rate, means responsive to abnormal changes eected in saidrate by the action of said cutting teeth during cutting to change saidpressure diiferential in a manner to reestablish said predeterminedrate, a second pump for supplying fluid to said second motor,connections between the said pump and motor including a reversing valve,and means trip operable by the table for controlling the shifting ofsaid valve.

13. Transmission means for control of the table of a milling machinehaving a tool spindle and a toothed cutter supported for rotationthereby and a work table actuable in a direction parallel to thedirection of movement of the teeth of said cutter while cutting, saidtransmission means including a piston and cylinder, one of which isoperatively connected to the table, a constant high pressure pump fordelivering fluid to said cylinder, a servo-valve for connecting saidpump in a manner to create equal resultant pressures in opposite ends ofsaid cylinder to hold the table against movement, a second hydraulicmotor for adjusting said servo-valve to create a s'uicient pressurediiferential to cause feeding movement of the table at a predeterminedrate, means responsive to abnormal changes effected in said rate by theaction of said cutting teeth during cutting to change said pressurediiferential in a manner to re-establish said predetermined rate, a pumpfor supplying fluid to said second motor, a feed rapid traverse selectorvalve and a reversing valve for connecting said last-named pump andmotor, and a dog carried by the table for controlling trip actuation ofeach of said valves.

HANS ERNST. MARIO E. MARTELLOTTI. WALTER D. ARCHEA.

